Cytotoxicity of LDL to cultured human fibroblasts. Treatment of fibroblasts was as in Materials and Methods. Bars refer to the percent of viable fibroblasts remaining after incubation with 200 μg protein of either control LDL, or LDL from β-thalassemia intermedia patients, for 24 hours (full bars) or 48 hours (shaded bars). Each value is the mean ± SD of values obtained with n LDL samples from different healthy controls or patients, each examined in duplicate. Control LDL, n = 12; minimum oxidized LDL (min-ox LDL), n = 11; medium oxidized LDL (med-ox LDL), n = 14; maximum oxidized LDL (max-ox LDL), n = 10. With respect to fibroblasts incubated for the relevant time * with control LDL, P < .001; ** with min-ox LDL, P < .001; *** with med-ox LDL, P < .001; Student’s t-test.